1. Field of the Invention
The present invention relates to an electrophotographic light-receiving member having sensitivity to electromagnetic waves such as light (including ultraviolet rays, visible rays, infrared rays, X-rays, .gamma.-rays and the like).
2. Description of the Related Art
In the field of image formation, photoconductive materials used for forming a light-receiving layer in an electrophotographic light-receiving member are required to have properties such as high sensitivity, high SN ratio, absorption spectral properties which conform with the spectral properties of the electromagnetic wave applied thereto, high photoresponsiveness, desired dark resistance values, harmlessness to human bodies during use and the like.
A photoconductive material found to have such excellent properties is amorphous silicon (referred to as "A-Si" hereinafter). For example, Germany Patent Laid-Open Nos. 2746967 and 2855718 disclose the application of A-Si to an electrophotographic light-receiving member.
Japanese Patent Laid-Open No. 57-11556 discloses a technique in which a surface barrier layer made of a non-photoconductive amorphous material containing silicon and carbon atoms is provided on a photoconductive layer made of a silicon-based amorphous material for the purpose of attempting to improve the electrical, optical and photoconductive properties, such as the dark resistance value, photosensitivity, photoresponsibility and the like, of a photoconductive member having a photoconductive layer comprising an A-Si deposited film, the working environmental properties thereof such as humidity resistance and the like, and the time stability.
In addition, Patent Application No. 62-168161 discloses a technique which uses as a material for a surface layer a material consisting of an amorphous substance containing as components silicon atoms, carbon atoms and 41 to 70 atomic% of hydrogen atoms.
Further, Patent Application No. 60-67951 discloses a technique for a photosensitive material in which a light-transmitting insulating overcoat layer containing amorphous silicon, carbon, oxygen and fluorine is laminated on the photosensitive material.
The above techniques permit improvement in the electrical, optical and photoconductive properties of an electrophotographic light-receiving member, the working environmental properties and durability thereof, and the quality of the image formed.
On the other hand, as the copying speed, the printing speed (image forming speed) and durability of an electrophotographic apparatus are rapidly increased, the frequency of maintenance must be decreased for decreasing the service cost by improving the reliability of each of the parts of the apparatus. In these circumstances, an electrophotographic light-receiving member can be continuously repeatedly used under various environmental conditions for a longer time, without being subjected to maintenance by a service man.
In this situation, the fact is that conventional electrophotographic light-receiving members have room for improvement.
Particularly, the repeated use of the members at a high speed for a long time under high humidity sometimes causes the phenomenon that the fine lines on the image formed are blurred (image flowing), and in the extreme case, the characters of the image cannot be read. In addition, once an electrophotographic light-receiving member in an electrophotographic apparatus produces the above phenomenon, it will continue to produce image blurring even if it is returned to environmental conditions under relatively low humidity which previously produced no image blurring. In a conventional method of preventing such image blurring caused under high humidity, a drum is heated for decreasing the relative humidity on the surface of the drum. However, this method requires heating of the surface of the drum to an extremely high temperature. Thus, the cost of the apparatus and the electricity consumption are increased, and the toner used sometimes adheres to the surface of the drum depending upon the set temperature.
In addition, when a light-receiving member having a hard surface with high durability is repeatedly used for a long time, as described above, the toner used sometimes adheres to the drum (filming), producing nonuniformity in density and blurs on the image formed.